Negative pressure slider with optimized leading pocket for profile control

ABSTRACT

Disclosed is a negative pressure air bearing slider having at least one trailing edge pocket defined by a generally U-shaped rail open to the trailing edge of the slider, and at least one leading edge pocket defined by a generally U-shaped rail open to the leading edge of the slider. Also disclosed is a method for determining an optimal width for a leading edge pocket of predetermined length and depth to provide a flat fly height profile in combination with a trailing edge pocket of predetermined dimensions. For a given trailing edge pocket configuration, width optimization is achieved by constructing a number of prototype sliders, each having a unique leading to trailing edge pocket width ratio; measuring the inner and outer diameter fly heights for each prototype to obtain ID and OD fly height profile curves; and determining a leading edge pocket width corresponding to the point of intersection of the curves.

This application is a division of application Ser. No. 08/149,861, filedon Nov. 10, 1993, entitled "NEGATIVE PRESSURE SLIDER WITH OPTIMIZEDLEADING POCKET FOR PROFILE CONTROL", in the names of Lee K. Dorius andLaurence S. Samuelson, and now abandoned.

BACKGROUND OF THE INVENTION

The present invention relates generally to negative pressure air bearingsliders for use in a disk drive, and more particularly to a negativepressure slider having one or more trailing edge pockets in combinationwith one or more optimized leading edge pockets for a flat fly heightprofile.

Conventional "positive" air bearing sliders ride on a cushion of airgenerated by the rotation of a magnetic disk. The upward force on theslider provided by the air cushion is directly proportional torotational velocity, and hence varies from the inner disk diameter (ID),to the outer disk diameter (OD). Since air bearing sliders tend to besensitive to such changes in upward-force, their fly height will varyacross the disk. A plot showing the variation in a slider's flyingheight from the ID to OD represents the "fly height profile" of thatslider. It is generally desirable to optimize a slider to provide a flatfly height profile.

Typically, a positive air bearing slider displays an increase in flyheight with increasing velocity. To obtain a more constant fly heightprofile, some slider designs include a trailing edge negative pressure"pocket". The pocket is generally formed by providing a cross-barbetween the "catamaran" rails of a slider, thereby forming a U-shapedair bearing surface (ABS) opening out to the slider's trailing edge. Aslider having a negative pressure pocket is referred to in the art as anegative pressure air bearing slider. An example of one such negativepressure air bearing slider is disclosed in U.S. Pat. No. 4,475,135.

Although U-shaped negative pressure air bearing sliders are animprovement over positive pressure designs, their fly height profilesstill tend to increase with increasing velocity. This tendency is due tothe fact that the negative pressure generated by the pocket cannot fullycompensate for the positive pressure of the catamaran rails. Tocounteract this problem, Some negative pressure sliders include a secondU-shaped pocket opening out to the leading edge of the slider. This typeof negative pressure slider has a generally H-shaped ABS. The leadingedge pocket channels move air over the cross-bar, thereby generatinggreater negative pressure in the trailing edge pocket to improve itsefficiency. An example of one such negative pressure slider is disclosedin U.S. Pat. No. 3,855,625.

One problem associated with H-shaped designs, however, isovercompensation resulting from the generation of too much negativepressure. A leading edge pocket having the same width as the trailingedge pocket generally has a linear fly height profile showing decreasingfly height from ID to OD. One solution has been to vary the etch depthof the trailing edge pocket to even out the profile. This designrequires a more complex manufacturing process than a slider with pocketsat the same etch depth. Another alternative has been to recess the crossbar between the catamaran rails. The recessed cross bar permits air flowfrom the leading edge pocket to vent into the trailing edge pocket,thereby decreasing the efficiency of the latter. A slider having arecessed cross-rail is disclosed in U.S. Pat. No. 4,218,715. But thisalternative also requires a more complicated manufacturing process. Whatis needed is a method for optimizing the leading and trailing edgespockets of a negative pressure slider having substantially the same etchdepth.

As an additional consideration, the negative pressure air bearingsliders described above produce large negative loads, and hence havehigh stiffness. Consequently, disk degradation due to slider impact withasperities is increased. A number of alternative negative pressure airbearing sliders optimize the amount of negative pressure while retainingthe benefits of negative pressure designs. Optimization mechanismsinclude reduction in pocket size, positioning of the pocket, anddistribution of the negative load between two or more pockets.Application Ser. No. 07/967,359 filed on Oct. 28, 1992 discloses suchoptimized designs and is incorporated herein by reference. What isneeded, for a given trailing edge pocket slider design and in a diskdrive having given inner and outer diameter fly height tolerences, is amethod for determining a leading edge pocket design optimized to providea desired slider fly height profile.

SUMMARY OF THE INVENTION

The present invention relates to a method for optimizing the fly heightprofile of a negative pressure air bearing slider having leading andtrailing edge pockets of substantially equal etch depth, and proposedoptimized negative pressure slider designs. An optimal leading edgepocket width is empirically selected by plotting fly height versusleading edge to trailing edge pocket width ratio for a slider positionedat the ID and a slider positioned at the OD. A leading edge pocket widthis then selected which corresponds to a desired fly height variationbetween the two curves.

It is therefore an object of the present invention to provide a methodfor optimizing the fly height profile of a negative pressure air bearingslider which is suitable for a variety of trailing edge pocketconfigurations.

It is a further object of the present invention to optimize the slider'sfly height profile by forming one or more leading edge pockets on theABS, each having an optimized width for a desired leading edge pocketdepth and length.

It is yet another object of the present invention to empiricallydetermine a leading edge to trailing edge pocket width ratio whichminimizes slider fly height profile variation.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features and advantages of the presentinvention will be apparent from the following detailed description ofthe preferred embodiments of the invention, reference being made to theaccompanying drawings, in which like reference numerals indicate likecomponents and in which:

FIG. 1 is a simplified block diagram of a magnetic disk storage systemembodying the present invention;

FIG. 2 is a perspective view of a negative pressure air bearing sliderwith a trailing edge pocket;

FIG. 3 is a perspective view of a negative pressure air bearing sliderwith leading and trailing edge pockets of equal width and depth;

FIGS. 4(a)-(g) are plan views of a negative pressure air bearing sliderhaving a trailing edge pocket of fixed dimensions and a leading edgepocket of varying width.

FIG. 5 is a graph showing the inner and outer diameter fly height curvesfor a slider having a trailing edge pocket of fixed dimensions andvarying leading edge widths; and

FIG. 6 is a preferred embodiment of the present invention having atrailing edge pocket and a leading edge pocket of optimal width; and

FIGS. 7-17 are alternative preferred embodiments of the presentinvention having one or more trailing edge pockets and one or moreleading edge pockets of optimized total width.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to FIG. 1, a magnetic disk storage system comprises atleast one rotatable magnetic disk 12 supported on a spindle 14 androtated by a disk drive motor 18 with at least one slider 13 positionedon the disk 12, each slider 13 supporting one or more magneticread/write transducers 21, typically referred to as read/write heads.The magnetic recording media on each disk is in the form of an annularpattern of concentric data tracks (not shown) on disk 12. The locationof the innermost data track on disk 12 is sometimes referred to as the"inner diameter" or ID 7 of the disk 12. Similarly, the location of theoutermost data track is sometimes called the "outer diameter" or OD 8.As the disks 12 rotate, the sliders 13 are moved radially in and outover the disk surface 22 so that the heads 21 may access differentportions of the disk where desired data is recorded. Each slider 13 isattached to an actuator arm 19 by means of a suspension 15. Thesuspension 15 provides a slight spring force which biases the slider 13against the disk surface 22. Each actuator arm 19 is attached to anactuator means 27. The actuator means as shown in FIG. 1 may be a voicecoil motor (VCM), for example. The VCM comprises a coil moveable withina fixed magnetic field, the direction and velocity of the coil movementsbeing controlled by the motor current signals supplied by a controller.

During operation of the disk storage system, the rotation of the disk 12generates an air bearing between the slider 13 and the disk surface 22which exerts an upward force or lift on the slider. The air bearing thuscounterbalances the slight spring force of the suspension 15 andsupports the slider 13 off and slightly above the disk surface by asmall, substantially constant spacing during operation.

The various components of the disk storage system are controlled inoperation by control signals generated by control unit 29, such asaccess control signals and internal clock signals. Typically, thecontrol unit 29 comprises logic control circuits, storage means and amicroprocessor, for example. The control unit 29 generates controlsignals to control various system operations such as drive motor controlsignals on line 23 and head position and seek control signals on line28. The control signals on line 28 provide the desired current profilesto optimally move and position a selected slider 13 to the desired datatrack on the associated disk 12. Read and write signals are communicatedto and from read/write heads 21 by means of recording channel 25.

The above description of a typical magnetic disk storage system, and theaccompanying illustration of FIG. 1 are for representation purposesonly. It should be apparent that disk storage systems may contain alarge number of disks and actuators, and each actuator may support anumber of sliders.

FIG. 2 shows a negative pressure air bearing slider which has been usedwith magnetic storage systems such as the system of FIG. 1. The sliderincludes a lower surface 9, an upper surface 10, leading and trailingedges 31, 32, and left and right side edges 33, 34. In normal systemoperation, the lower surface 9 is facing downward as the slider 13 fliesin close proximity to the magnetic recording disk 12. The-lower surface9 shown comprises an inverted U-shaped rail 36 defining a trailing edge(TE) negative pressure recess or pocket 30. Rail 36 includes a crossrail 37 and a pair of side rails 38, 39. The cross rail 37 has a taperedregion 35 at the leading edge (LE) 31 of the slider 13 to assist initiallift-off. In operation, as the disk 12 begins to rotate, air flowgenerated by the rotation travels across lower surface 9 in thedirection of the arrow 8, thereby exerting a positive pressure on rail36 sufficient to lift the slider 13 off of the disk. Simultaneously, anegative, suction-like pressure is generated by air flowing into the TEpocket 30 to counteract the positive force and stabilize the slideragainst changes in velocity.

FIG. 3 shows an alternative negative pressure air bearing slider whichhas also been used with storage systems such as that of FIG. 1. Thelower surface 9 of this slider comprises a U-shaped rail 41 defining aleading edge (LE) recess or pocket 40, and an abutting inverted U-shapedrail 36 defining a TE pocket 30. The LE rail 41 shares a common crossrail 37 with the TE rail 36, and further includes left and right siderails 43, 44, each having a tapered portion 35 along leading edge 31. Inthe embodiment shown, LE pocket 40 and TE pocket 30 are of substantiallyequal width. In operation, LE pocket 40 enhances the effect of thenegative pressure generated in TE pocket 30 in proportion to increasingvelocity, i.e., as the slider moves from ID to OD.

FIGS. 4(a)-(g) and 5 illustrate an example of the optimization methodaccording to the present invention. The process begins by selecting anegative pressure air bearing slider with a desired TE pocketconfiguration. For illustration purposes, the simple negative pressureslider of FIG. 4(a) is selected. The slider has a single TE pocket 50 offixed depth and fixed width 56 defined by inverted U-shaped rail 51. TErail 51 includes cross rail 52 with tapered portion 55 adjacent to theleading edge 31, and left and right side rails 53, 54 extendingperpendicularly from cross rail 52 to the trailing edge 32. The left andright side rails 53, 54 are adjacent to the left and right side edges33, 34 of the slider, respectively.

Next, a series of prototypes are formed by conventional methods with thesame TE pocket dimensions as the selected slider, and also including LEpockets of fixed depth and length, but of varying widths. The LE pocketsmay be formed by the same conventional methods, e.g., by chemicaletching, reactive ion etching (RIE), or ion milling. In the examplegiven, the LE pocket widths Of the prototypes shown in FIGS. 4(b)-(g)have been carefully selected to provide sliders with LE to TE pocketwidth ratios of 0.2, 0.4, 0.6, 0.8, 1.0 and 1.2, respectively. Forexample, FIG. 4(b) shows a prototype having a TE pocket 50 identical tothat of FIG. 4(a), and a LE pocket 60 of fixed depth, a fixed length 68and a selected width 70. The ratio of LE pocket width 70 to TE pocketwidth 56 is 0.2. For simplicity of manufacture, the LE pocket depth maybe equal to that of the TE pocket 50, but this is a matter of preferencerather than a requirement of the method disclosed.

Next, each prototype slider is flown over a recording disk in order tomeasure its average fly height at ID and OD. The fly height informationis then recorded on a plot such as that shown in FIG. 5. The horizontalaxis 82 represents increasing LE to TE pocket width ratios ranging from0.0 to 1.4, and the vertical axis 81 represents average slider flyheight in nanometers. For example, the prototype slider of FIG. 4(b) wasexperimentally found to have an average fly height of approximately 85nm at the ID, represented by point 86, and an average fly height ofapproximately 175 nm at the OD, indicated by point 85. After the ID andOD fly heights for each prototype have been measured, two curves 83, 84are obtained. Curve 83 is obtained by connecting the points representingthe OD fly heights measured for each slider prototype. It provides anapproximation of OD fly height variation for a slider of fixed TE pocketdimensions and increasing LE pocket widths at fixed depth. Similarly,curve 84 approximates the ID fly height variation for a slider of fixedTE pocket dimensions and increasing LE pocket widths at fixed depth.

The intersection of the curves 83, 84 occurs at a point 87 in which theID and OD average fly heights for a given LE pocket width areapproximately equal. The pocket width ratio 88 corresponding to thepoint of intersection 87 provides the optimal slider configuration forthe selected slider to provide a flat fly height profile from ID to OD.In the example given, a LE to TE pocket width ratio of approximately 0.9was found to correspond to intersection point 88. Using thisinformation, an optimized slider may now be manufactured. FIG. 6 showsthe optimized slider design obtained in the foregoing example. TE pocket50 is identical to that of FIG. 4(a). The depth and length 68 of LEpocket 60 are fixed at the same dimensions selected for the prototypesof FIGS. 4(b)-(g), but the width 76 has been carefully selected so thatthe ratio of LE pocket width 76 to TE pocket width 56 is approximately0.9. Although the prototypes of the foregoing example were chosen toprovide LE to TE pocket width ratios in increments of 0.2, it should beunderstood that increments of smaller or larger dimension may beselected, depending on the precision desired in a particular case.

In some disk drives, variations in fly height tolerences between ID andOD make it desirable to select a pocket width ratio corresponding tosome point other than the point at which average ID and OD fly heightsfor a fixed LE pocket width are equal. For example, in a disk drive withdifferent ID and OD fly height tolerances, an optimal slider may be onein which the average ID and OD fly heights vary by 10 nm. In such cases,a pocket width ratio is selected which corresponds to the desiredvariation between the average ID and OD fly height curves. Referring toFIG. 5, dashed line 72 references the pocket width ratio 71approximately Corresponding to a 10 mm variation between the curves 83,84. Hence, pocket width ratio 71 provides the optimal LE pocket widthfor the given tolerances of this case.

FIGS. 7-14 show negative pressure sliders with various TE pocketconfigurations which further include one or more leading edge pocketsoptimized according to the present invention. The slider of FIG. 7 has aLE pocket 100 defined by a U-shaped rail 99, and a TE pocket 90 definedby an inverted U-shaped rail 89 abutting rail 99. The left and rightside rails 101, 102 of rail 99 are adjacent to left and right side edges33, 34, respectively, and include tapered portions 103, 104 adjacent tothe slider's leading edge 31. The TE rail 89 shares a common cross rail91 with LE rail 99. It further includes left and right side rails 92, 93which extend perpendicularly from common cross rail 91 in the directionof the trailing edge 32 along left and right side edges 33, 34,respectively. TE pocket 90 is bisected by a center rail 96 .extendingperpendicularly from the center of cross rail 91. The center rail 96balloons into an island 97 adjacent to and centered with respect to thetrailing edge 32. The island 97 provides a convenient surface forsupporting a magnetic transducer (not shown). An optimized LE pocketwidth 106 was chosen by applying the optimizing method described above.A number of prototype sliders were constructed with the same TE pocketconfiguration as shown in FIG. 7, and with LE pockets of fixed depth andlength 105, but of varying widths. The ID and OD fly heights for eachprototype were measured and curves similar to those of FIG. 5 wereplotted. The ID and OD curves were found to intersect at a pointcorresponding to optimal LE pocket width 106.

FIGS. 8 and 9 show negative pressure air bearing sliders having analternative TE pocket configuration. In FIG. 8, pair of catamaran-typeside rails 131, 132 extend perpendicularly from leading edge 31 alongleft and right side edges 33, 34 in the direction of trailing edge 32.Each catamaran rail 131, 132 includes a tapered portion 133, 134adjacent to the leading edge 31 to assist slider lift-off. U-shaped rail119 and abutting inverted U-shaped rail 109 are disposed in between thecatamaran rails 131, 132 and define leading and trailing edge pockets120, 110. Rails 119 and 109 are isolated from the catamaran rails 131,132 by a pair of slots 135, 136. Common cross rail 111 is parallel toleading edge. 31. The left and right side rails 121, 122 of rail 119extend perpendicularly from common cross-rail 111 to leading edge 31.Each includes a tapered portion 123, 124 adjacent to the leading edge 31for further assisting slider lift-off. Left and right side rails 112,113 of rail 109 extend. perpendicularly in the opposite direction fromcross rail 111. As is apparent from FIG. 8, the catamaran rails 131, 132extend farther in the direction of the trailing edge 32 than the leftand right side rails 112, 113. An island 117 is disposed adjacent to andcentered with respect to the trailing edge 32 and provides a convenientsurface for supporting a read/write transducer (not shown).

The slider shown in FIG. 9 is essentially the same as that of FIG. 8,with two exceptions. Each catamaran rail 161, 162 includes a flaredportion 167, 168 which acts to increase roll stiffness. Moreover, theslider design has been optimized for a lower suspension preload thanthat of FIG. 8. Consequently, the LE pocket 150 has a narrower optimalwidth 156 than LE pocket 120, and island 147 is smaller and morestreamlined than island 117.

FIGS. 10 and 11 illustrate yet another TE pocket configuration withoptimized LE pockets. In FIG. 10, left and right TE pockets 170, 190 aredefined by generally U-shaped left and right rails 169, 189 withextended outer side rails 172, 192. The extended side rails 172, 192 runadjacent to respective left and right side edges 33, 34, and includeflared portions 176, 196. A pair of LE pockets 180, 200 are defined byU-shaped rails 179, 199 abutting LE rails 169, 189. The side rails 181,182, 201, 202 of LE rails 169, 189 extend to leading edge 31, and havetapered portions 183, 184, 203, 204 directly adjacent to the leadingedge 31 for enhanced slider lift-off. The outer side rails 183, 204 arealso adjacent to the left and right side edges 33, 34. A center rail 210with a flared portion 212 and a tapered portion 211 extends from leadingedge 31 to trailing edge 32. The center rail is isolated from the innerside rails 184, 173, 203, 193 by channels 213, 214. The LE pockets 180,200 are selected in a manner similar to that described in theoptimization example above. A series of prototype sliders having a pairof TE pockets identical to those of FIG. 10 are constructed byconventional methods. One prototype has no LE pockets. Each of theremaining prototypes includes a pair of identical LE pockets 180, 200 offixed depth and length 185, 205, but of varying incremental widths. TheLE pockets of a prototype may have identical or different widths.Average ID and OD fly heights for each prototype are measured andplotted to obtain ID and OD curves. In contrast to the previous example,however, two separate graphs are created. A first graph charts the IDand OD fly heights corresponding to incremental pocket width ratios ofthe left-hand pockets, i.e., LE pocket 180 to TE pocket 170. A secondgraph represents fly heights corresponding to the incremental ratios ofthe right-hand-pockets, i.e., LE pocket 200 to TE pocket 190. The LEpocket width corresponding to the point of intersection of the curves ineach graph provides the pocket width of the respective LE pocket to beincorporated in the slider design of FIG. 10.

The slider of FIG. 1t is essentially the same as that of FIG. 10, withthe exception of inner side rails 223, 243 of the TE rails 219, 239,which include indented portions 227, 247 running parallel to the flaredportion 262 of center rail 260. This design has been optimized for lowersuspension preload and lower file RPM than that of FIG. 10.Consequently, the optimal LE pocket widths 236, 256 are much narrowerthan those of FIG. 10.

FIG. 12 shows a negative pressure slider design similar to that of FIG.6. The side rails 272, 273 of TE rail 269 generate the positive pressurelift. The LE pocket 280 is narrower than the TE pocket 270. The ratio ofthe LE pocket width 286 to the TE pocket width 274 is optimized toflatten out the ID-OD head/disk spacing profile. The narrower LE pocketwidth 286 reduces the amount of negative load generated by the TE pocket270, allowing control of the air bearing stiffness. The dashed line 276illustrates the possibility of shortening either one of the side rails272, 273 in order to raise the minimum slider flying height in skewedfile environments. It should also be understood that both side rails maybe shortened and a center island added at the trailing edge toaccommodate centered transducer element designs.

FIG. 13 shows a negative pressure slider design in which LE pocket 300is offset to the left with respect to TE pocket 290. Such geometryprovides optimal spacing profile control in highly asymmetric ID vs ODskew file environments. The offset LE pocket 300 serves to create awider leading edge side rail 304 which generates an offsetting rollmoment in the highly skewed condition. In an alternate embodiment, LEpocket 300 is offset to the right. As in FIG. 12, dashed line 296indicates that one of the trailing edge side rails 292, 293 may beshortened.

FIG. 14 illustrates a negative pressure slider design having twolocalized TE pockets 310, 330. Each pocket 310, 330 has an outer siderail 312, 332 extending along a respective side edge 33, 34 to thetrailing edge 32 of the slider, and a shorter inner rail 313, 333. Theouter rails include flared portions 315, 335 for controlling themagnitude and location of the generated negative pressure. The railflares 315, 335 also help increase the slider pitch and roll stiffness.The design includes a pair of LE pockets 320, 340 corresponding to TEpocket 310, 330. The LE pockets widths 326, 346 may be optimizedindependently, as may the LE pocket offsets with respect to the TEpockets 310, 330 to achieve the desired ID-OD head/disk spacing profile.The dashed line 316 again indicates the option to shorten a TE pocketside rail.

FIG. 15 shows the slider of FIG. 14 with a single LE pocket 420. Thewidth 426 of the LE pocket 420 provides control of the negative pressuregenerated in TE pocket 330.

FIG. 16 shows a LE/TE pocket combination 369 disposed within twocatamaran-type side rails 381, 382. The catamaran rails 381, 382 extendfrom leading edge 31 to trailing edge 32 along respective side edges 33,34 of the slider. The pocket combination 369 is connected to the leadingedge 31 by side rails 371, 372. It should be understood that thecombination 369 need not be centered with respect to the catamaran rails381, 382 and may be offset to either side to optimize skew performance.Likewise, the size of the combination and offset of LE pocket 370 withrespect to TE pocket 360 may also be varied.

FIG. 17 shows a negative pressure slider design similar to that of FIG.16 except that the LE/TE pocket combination 399 is not connected to theleading edge 31 of the slider. Again, it should be understood that thecombination 399 may be varied in size, LE to TE offset, and offset withrespect to catamaran rails 411, 412 to optimize skew performance.

It should further be understood that the dashed lines in FIGS. 12-17indicate that one outer rail in each of the embodiments shown may beshortened in order to raise the minimum fly heights in skewedenvironments. Alternatively, both side rails may be shortened and acentered trailing edge island pad may be added in order to accommodatecentered transducer element designs.

While a specific example of the method and a number of specificembodiments of the apparatus of the present invention have beendescribed, it will be understood that various modifications and changesmay be made to either without departing from the spirit and scope of theinvention. Accordingly, the invention is not to be limited by theforegoing examples, but only by the scope of the following claims.

We claim:
 1. A negative pressure air bearing slider for use in a diskdrive, said slider including a leading edge, a trailing edge, first andsecond side edges, and an air bearing surface, said air bearing surfacefurther comprising:two TE pockets, each defined by a generally U-shapedrail including a cross rail and a pair of side rails extending from saidcross rail in the direction of said trailing edge; a center raildisposed between and spaced apart from said TE pockets extending fromsaid leading edge to said trailing edge; and two LE pockets, eachdefined by a generally U-shaped rail including a cross-rail and a pairof side rails extending from said cross rail in the direction of saidleading edge, wherein said U-shaped rail of each LE pocket abuts one ofsaid U-shaped rails of said first and second TE pockets.
 2. The sliderof claim 1, wherein said center rail includes a flared portion at saidtrailing edge.
 3. The slider of claim 1, wherein the depth of at leastone LE pocket is substantially equal to the depth of said abutting TEpocket.
 4. The slider of claim 1, wherein a side rail of each TE pocketis adjacent to one of said first and second side edges.
 5. The slider ofclaim 1, wherein at least one side rail of said at least one LE pocketextends to said leading edge.
 6. The slider of claim 5, wherein said atleast one side rail of at least one LE pocket further includes a taperedportion at said leading edge.
 7. The slider of claim 1, wherein a siderail of at least one LE pocket is adjacent to one of said first andsecond side edges.
 8. A storage device, comprising:a movable storagemedium; a transducer positionable relative to the storage medium andsupported on a negative pressure air bearing slider including a leadingedge, a trailing edge, first and second side edges, and an air bearingsurface facing the medium, said air bearing surface furthercomprising:two TE pockets, each defined by a generally U-shaped railincluding a cross rail and a pair of side rails extending from saidcross rail in the direction of said trailing edge, a center raildisposed between and spaced apart from said TE pockets extending fromsaid leading edge to said trailing edge, and two LE pockets, eachdefined by a generally U-shaped rail including a cross-rail and a pairof side rails extending from said cross rail in the direction of saidleading edge, wherein said U-shaped rail of each LE pocket abuts one ofsaid U-shaped rails of said first and second TE pockets.
 9. The storagedevice of claim 8, wherein said center rail includes a flared portion atsaid trailing edge.
 10. The storage device of claim 8, wherein the depthof at least one LE pocket is substantially equal to the depth of saidabutting TE pocket.
 11. The storage device of claim 8, wherein a siderail of each TE pocket is adjacent to one of the first and second sideedges.
 12. The storage device of claim 8, wherein at least one side railof at least one LE pocket extends to said leading edge.
 13. The storagedevice of claim 12, wherein said at least one side rail of said at leastone LE pocket further includes a tapered portion at said leading edge.14. The storage device of claim 8, wherein a side rail of at least oneLE pocket is adjacent to one of said first and second side edges.